A fluid friction clutch of said type is known from EP 1 731 787 B1, the content of disclosure of which is hereby incorporated by explicit reference to the content of disclosure of the present application.
DE 197 49 342 A1 discloses a viscous clutch for driving motor vehicle air-conditioning compressors, in which, to control the filling level of fluid in a working chamber, the throughput of fluid through the pipe section adjoining an inlet section of a scoop pipe is controlled by means of a valve. Tests carried out within the context of the invention have, however, revealed that such a valve causes problems in that it is extremely difficult to achieve acceptable performance results.
It is therefore an object of the present invention to provide a fluid friction clutch, by means of which it is possible in a simple manner, without using a valve, to achieve a variable clutch fluid flow.